This invention relates to shock absorbing and support pads for a missile launching system and more particularly to a shock isolation and support system which has two separate deflection mechanisms incorporated therein.
Missile launch systems have used multiple rows of cast elastomeric shock absorbing pads to line the launch tube wall and laterally support the missile as described in U.S. Pat. No. 4,406,211. Such lateral support systems are used to maintain stored missile alignment, limit shock and vibration inputs to the missile, and control lateral excursion of the missile during the launch. The circular arc-shaped pads herebefore utilized are comprised of a multitude of prebuckled chevron-shaped struts which serve as isolation elements. The pressure deflection curves of thes pads with the chevron strut design can be characterized: as initially pressure rises sharply from small deflections, then the pressure remains fairly constant for an appreciable amount of deflection, and finally as the struts begin to fall flat or bottom out the pressure rises sharply with small deflections. The amount of pad precompression needed to provide proper lateral support with various launcher and missile tolerance buildups tends to create high axial friction forces due to the initial pressure to deflection characteristics and thus impairs on-loading, off-loading and launch of the missile.
Another general problem with chevron strut elastic elements utilized in the prior art systems is that the load path and strut geometry can suddenly change dramatically with small changes in applied loads or load direction. The circular arc shaped pads presently used incorporate shear struts to minimize this tendency, but the shear struts complicate the manufacturing process and do not completely eliminate the problem.
The dual plateau pads described in the related application noted above was developed to satisfy the shock and vibration mitigating requirements, while limiting the axial friction loads between the missile and the support system. The corrugated face of these pads are designed to compress before the chevron-shaped struts begin to deflect. Thus the corrugations are to take the amount of precompression required to compensate for the tolerance buildup in the missile and launch system. However, the prebuckled chevron-shaped struts and corrugation contact surface do not provide the optimum method of transferring the load to the missile skin or outer surface, and the segmented pads tend to collapse and pull away from the missile as eject pressure flows by during the launch.